Dry lubricant coated article

ABSTRACT

A MEMBER OF A BASE METAL SUCH AS ALUMINUM, MAGNESIUM, TITANIUM OR TIN IS ELECTROLYTICALLY ANODIZED WHILE SIMULTANEOUSLY ELECTROPHORETICALLY DEPOSITING SOLID LUBRICANT PARTICLES OF COLLOIDAL SIZE, SO AS TO PRODUCE A LUBRICATING COATING TIGHTLY BONDED TO THE SURFACE OF THE MEMBER WITH THE PARTICLES BEING DISTRIBUTED THROUGHOUT THE THICKNESS OF AN OXIDE ON THE SURFACE AND BEING LOCKED IN PLACE WITHIN RANDOMLY ORIENTED INTERSTICES WITHIN THE OXIDE. PREFERABLY, THE SOLID LUBRICANT PARTICLES ARE OF TEFLON AND THE BASE METAL IS ALUMINUM, BUT VARIOUS OTHER SOLID LUBRICANT PARTICLES AND BASE METALS MAY BE USED.

its. c1. 204-56 R a,ss,111

DRY LUBRICANT COATED ARTICLE illa lph 'J. Hovey,.1N600 Glenrise Ave., Glen Ellyn, Ill.

60137, and Afsar A. Khan, 921 Cedar Ave.," Elmhurst, Ill. 60126 No Drawing. Continuation of applicationSer. No.

" T QABSTRACT or THE DISCLOSURE Am'ember of a' base metal such as aluminum, magnei'siu'r'n, titanium or tin is electrolytically anodized while simultaneously electrophoretically depositing solid-lubri- 'c'antparticles of colloidal size, so as to produce a lubricating coating tightly bonded to the surface of the member with the particles being distributed throughout the thickness of an oxide on the surface and being locked .i'nplac'e within randomly oriented interstices within the 'oxide'pPreferably, the solidlubricant particles are of Teflon and the base metal is aluminum, but various other solid lubricant particles and base metals may be used.

This is a continuation of application Ser. No. 879,551, filed Mar. 4, 1970, which is a continuation-in-part of application Ser. No. 832,476, filed June 11, 1969 and issued as US. 3,567,597, which is a division of, and which was copending with, application Ser. No. 520,360, filed, Jan.

3, 1966, now abandoned.

The invention relates to a dry lubricant coatedarticle. More particularly the invention relates to incorporating particles of a solid lubricant into the anodized surface of a metal to form adry lubricant coating.

An object of the invention is to provide a strongly ad herent dry lubricant coating.

A further object is to provide a method of quickly'and economically producing an anodized metal surface having superior lubricating qualities to that of an ordinary anodized surface. I

Another pbject is to provide a method of producing a dry lubricant comprising an anodized metal surface containing particles of a fluorocarbon polymer.

Other objects and advantages of the invention will become apparent as the following detailed description progresses.

In accordance with this invention an anodizable metal such as aluminum, titanium, tin or magnesium is electrolytically anodized as is well known to the art and while the anodization is taking place there is electrophoretically deposited on the metal particles of a solid lubricant. This simultaneous electrolytic growth of oxide and electrophoretic deposition of a lubricating media is accomplished by incorporating in the electrolyte being used for the anodization a negatively charged particle of a solid lubricant. Thus, when the metal is made the anode and oxidation is taking place by electrolysis at the anode, the negatively charged particles of solid lubricant will migrate by means of the electric current induced in the bath to the anode and will be commingled (mingled) with the oxide coating during its formation. By this procedure the particles are substantially uniformly distributed throughout the thickness of said oxide and are locked in place with randomly oriented interstices within said oxide to form with the oxide a lubricating coating tightly bonded to the surface of the base metal. This gives an extremely adherent low coeflicient of friction coating useful as a bearing surface and for other uses of dry lubricants.

.llnitedStatcs Patenti Q Patented I Apr. 30, 1974 Y The thickness of thecoatingis a function of the treatment time. Suitable coatings have been made with .001

inch-thickness and as thick as .005. inch, but lesser and greater thicknesses can be attained. I

The preferred metals used for simultaneous anodization and electrophoretic-deposition.of solid particles are aluminum, titanium, magnesium and the alloys containing a major portion. of such metals. The oxide coating produced is.better suited for the commingling (mingling) with solid lubricants such as fluorocarbon polymers, and

gives a superior lubricating coat than produced by anodizing tin.

All types of solid lubricant particles which normally .have or which can'be made to have alnegative charge .may be used. Thus particles of molybdenum disulphide,

alumina-tungsten disulphide, polyethylene, and fluorocarbon polymers can be used. For lubricating purposes the fluorocarbon polymers are preferred, particularly the completely .fluorinated fluorocarbon polymers, of which the best appears to be tetrafluoroethylene. The suitable fluorocarbon polymers include polytetrafluoroethylene, poly- EXAMPLE I An aluminum sheet is made the anode. The cathode is lead or stainless steel. The electrolyte consists of sulfuric acidv (10 fluid ounces per gallon), oxalic acid (2 40 ounces per gallon), an aqueous suspension of negative charged colloidal particles of polytetrafluoroethylene containing 0.5 percent by weight TFE (Teflon suspension N0. 3170) acidulated with 5 percent sulfuric acid, the ingredients being merged in water to a volume of two gallons. The electrolyte was contained in a glass tank and maintained at a temperature of 25 95 F. during the operation. The current density used was 10-36 amperes per square foot. The voltage was 10-75 volts. Vigorous agitation of the electrolyte was maintained. The time of operation was 15 to 60 minutes.

The coated plate produced by the above example had a coating of mixed aluminum oxide and particles of polytetrafluoroethylene of 0.002-0.0025 inch thickness.

Substantially the same results as with the above example may be obtained with the other fluorocarbon polymers above mentioned using similar procedure and conditions as in Example I. With particles of molybdenum disulphide and other. metal sulfides a suitable commingled (mingled) coati iig was also obtained by substituting a molybdenum disi lphide aqueous dispersion for the Teflon dispersion and otherwise keeping the conditions the same, although modification of the procedure to obtain better anodic deposition of the molybdenum disulphide could be carried out in accordance with procedures known to the art without interfering with the simultaneous anodization. Polyethylene does not give as satisfactory lubricating properties as the fluorocarbon polymers but can also be electrophoretically deposited during electro anodization using the procedure and condition of Example I.

The use of negatively charged colloidal particles as above disclosed for the electrophoretic deposition gives particles of colloidal size commingled (mingled) with the 'cedures of the example there is obtained an article comprising a'memb'er'of a base metal such as aluminum, an'

oxide of said base metal and of substantial thickness anodized on a surface of said member, and solid lubricant particles of colloidal size- ('.001-.5 micron diameter) mingled with said oxide, said particlesbeing substantially uniformly distributed throughout the thickness of said oxide and being locked in place within randomly oriented interstices within said oxide to form with said oxide a lubricating coating tightly bonded to-the surface 'of the base metal.

The resultant oxide has at least a portion of the particle of lubricant deposited in some interstices below the bearing or outer surface of the oxide with these interstices not normally accessible by direct treatment of the bearing surface with similarly sized particles of the lubricant I The above procedure of Example I may be'suitable for other anodizable metals including titanium and magnesium.

What is claimed is:

1. An article comprising a member of a base metal, an oxide of said base metal and of substantial thickness anodized on a surface of said member and including an upper surface opposite said member, and solid lubricant particles mingled with said oxide, said particles being substantially uniformly distributed throughout the thickness of said oxide and being locked in place within randomly oriented interstices within said oxide to form with said oxide a lubricating coating tightly bonded to said surface, at least a portion of said particles being deposited below said upper surface during formation of said oxide by anodizing.

2. An article as defined in claim 1 wherein the solid .lubricant particles are of colloidal size.

3. An article as defined in claim 2 wherein said base metal is aluminum.

4. An article as defined in claim 2, wherein said base metal is magnesium.

5. An article as defined in claim 2 wherein saidbase metal is titanium.

6. An article as defined in claim 2 wherein said solid lubricant particles are particles of a fluorocarbon polymer.

4 in claimf 2 whe1ein5said..snlid lubricant particles are particles of molybdenum sulphide. -8. The article of claim 6 wherein the base-metal is aluminum and wherein the particles are of polytetrafiuoroethylene.

9. An article as defined in claim Swherein said solid lubricant particles are electrophoretically deposited and mingled with said oxide during formatio'nof said'bxide on said surface of said member, and a major portion of said particles being in the range of 0.001-0,'5, micron in diameter. T 1

10. An'article comprising a member of a base metal, an oxide of said base metal and of substantial thickness anodized on a surface of said member, and including an upper surface opposite said member, and solid lubricant particles mingled with said oxide, said particles being substantially distributed throughout said oxide and being locked in place within randomly oriented interstices within said oxide to form with said oxide a lubricating coating tightly bonded to said surface, at least a'portion of said particles being electrophoretically deposited. below said upper surface during formation of said'ox'ide by anodizing.

11. An article as defined in claim 10 wherein the. base metal is aluminum and the particles are of polytetrafluoroethylene and are of colloidal size. j v. 12. An article as defined in claim 11 wherein said particles are deposited in an electroplating system comprising an anode of said base metal, a cathode, and an electrolyte containing said particles with a negative charge.

References Cited UNITED STATES PATENTS 3,716,348 2/1973 Perkins 117-75 3,711,313 1/1973 Nagand et al. 117-75 3,438,789 4/1969 Weiss et al.. 204-56 R 3,271,653 9/1966 Wolf 117-75 3,211,325 10/1965 Wisnicki 22064 3,052,590 9/1962 Maros et al. 11775 JOHN H. MACK, Primary Examiner R. L. ANDREWS, Assistant Examiner US. Cl. X.R. 204--58; 117-75 

